1. Field of the Invention
The present invention relates to a microwave generator, which includes a hollow central electrode having a front face with a hollow emission element and an outer electrode, which coaxially surrounds the central electrode along an axially extending resonator section.
The operation of a microwave generator such as the foregoing is based on a high-voltage source being short-circuited and thus discharged via a spark gap in the microwave generator. The high-voltage source may have a capacitor bank, which is charged in parallel on the basis of the principle of the Marx impulse-voltage circuit, and is then connected in series. As an alternative to the use of a Marx impulse-voltage circuit, that is to say of a Marx generator, it is also possible to use a high-voltage generator driven by explosives, which can produce a single high-voltage pulse with an extremely high pulse energy.
The short-circuiting of the high-voltage source via the spark gap creates highly oscillating discharge or short-circuit currents with a steep flank, which contain a mixture of very high frequencies which are emitted as, microwave energy via an emission element (in the form of an antenna) of the microwave; generator, with a broadband spectrum that is dependent on the respective frequency mixture. The broadband microwave spectrum has a very high energy density, so that, for example, radio traffic in the vicinity of a microwave generator such as this is at least adversely affected, and input circuits of electronic circuits can be interfered with, or in the extreme even destroyed, as a result of resonance effects.
2. Discussion of the Prior Art
DE 101 51 565 A1 discloses a microwave generator which has a high-voltage spark gap between electrodes which are arranged such that they are aligned axially.
On both sides of the spark, gap, the electrodes and their coaxial holders are accompanied over at least a portion of their axial longitudinal extent by an electrical conductor which runs at a distance from them and is electrically conductively connected to one of the two electrodes. In this known microwave generator, the spark gap is formed between a small electrode in the form of a mushroom head, and a relatively large electrode, in the form of a lobe. The electrode in the form of a lobe is surrounded by an outer conductor, which is connected via an appropriate connection structure to the electrode which is in the form of a mushroom head. The axial position of the connection structure may be moved together with the electrode which is in the form of a mushroom head by means of a spindle mechanism relative to the stationary, second electrode, for tuning purposes.
The prior DE patent application 10 2005 002 279 discloses a microwave generator having a central electrode which has arm emission element on the front face, and having an outer electrode which coaxially surrounds the central electrode along an axially extending resonator section, with the two electrodes being designed to be rotationally symmetrical and defining a spark gap which flashes over when a high voltage is applied, emitting microwaves via the emission element of the central electrode. This microwave generator essentially comprises the two metallic electrodes, specifically the central electrode with the emission element, and the outer electrode which coaxially surrounds it. The two electrodes are arranged in sealed form in an electrically insulating housing sleeve and can be charged from a pulsed high-voltage source simply by making contact with the two ends of the microwave generator, which are axially remote from one another. This represents a so-called two-wire feed for the microwave generator. The internal area of the microwave generator, which is defined by the two electrodes and the electrically insulating housing sleeve and is bounded in a sealed form, may be filled with a gaseous or with a liquid dielectric in order to increase the dielectric strength. By way of example, the gaseous dielectric may be SF6.
The last-mentioned form of the microwave generator is preferably formed by the high-voltage source being a Marx generator which is arranged at the side alongside the microwave generator and parallel to it, so that the voltage outputs which are provided at the mutually remote ends of the Marx generator can be connected to the axially mutually remote ends of the microwave generator. Although this ensures the optimum dielectric strength, the space required, that is to say the area required, is, however, correspondingly large because the high-voltage source is arranged at the side alongside the microwave generator.